The codebase has two alternate implementations of Envoy::Buffer. The legacy one is derived from libevent's buffer implementation, and has a ton of mileage on it, but also numerous known fuzzing issues.

A new one was created by @brian-pane which is off by default. There has been some fuzzing work done on it and it looks clean.

We should use this issue to collect experiences canarying the new buffer implementation, by adding command-line option:

   --use-libevent-buffers false

Potential canaryiers include: @moderation and @mattklein123 .

Once done we can (a) switch the default to use the new buffer implementation, and then later (b) drop the libevent implementation from the codebase, enabling some simplification.